Question

A mixture consists of sand and an aqueous salt

Answer 1

Answer is (4).

Explanation:

The given mixture contains an insoluble solid and an aqueous solution of salt.  The insoluble solid is sand. 

First we have to separate insoluble solid. Sand can be separated by doing filtration. When we filter the mixture sand can be seen as the residue on the filter paper. 

After filtering the mixture, we should collect the filtrate. Filtrate is the salt solution. By doing evaporation we can get the solid salt. 

First and second choices are wrong because after evaporating water filtration cannot be done and salt and sand will be mixed together.

Salt cannot be filtered out because the salt is soluble and it is in aqueous medium. Hence, third choice is wrong

Answer 2

The best answer is 4  because if you get rid of the sand first and evaporate the water you're left with salt